1. Field of the Invention
The present invention relates to swimming goggles, and particularly to swimming goggles which have an easily-adjustable head strap and are worn comfortably.
2. Related Art
Swimming goggles, generally, have buckles for accommodating and adjusting a head strap thereof. In prior art, buckles are respectively disposed on a left side and a right side of frames, and are assembled on two ends of a head strap for adjusting length. Each of the buckles comprises a biasing arm for abutting against the head strap. The biasing arm abuts against a serrated groove of the head strap in such a way that the head strap can be tightened merely in a single direction when the biasing arm does not abut the head strap (namely the head strap can be shortened only). The biasing arm has to be released for purpose of loosening the head strap. Thus, it is directly associated with adjustment of the head strap whether the biasing arm abuts against the head strap.
The prior art buckle, which controls abutment of the biasing arm, is commonly designed in compliance with a first lever principle to exert force on an end of a biasing arm, while the opposite end of the biasing arm acts in a reverse direction for releasing the biasing arm. At the same time, a resilient element acts on the end exerted force thereon for returning the biasing arm. In this way, whatever kind of assembly the resilient element has, two components are necessary to contact indirectly for manipulation. This makes manufacture and assembly more difficult, and increases cost. It is a desired issue how to improve the prior art buckles of the swimming goggles to meet the requirements of convenient use and simplified manufacture.